The kinetics of the formation reaction of a metal process depends on various factors. On an industrial level, for reasons of costs and concentrations, a direct reaction is performed, where possible, between a metal oxide (MO) or metal hydroxide (MOH) and an organic acid (HA) in aqueous solution. The reaction is typically a reversible equilibrium reaction, e.g. as follows:MO+2HAMA2+H2O
The presence of water and the pH considerably affect the reaction rate and the equilibrium point.
It is evident that, since water is one of the reaction products, water itself, as solvent, induces the hydrolysis process of the complex, thus shifting left the reaction.
In addition, certain complexing agents as well as certain metals, can be subjected, in their application, to physicochemical attacks of various nature that reduce their effectiveness, even to a complete ineffectiveness. Among many possible examples of such interactions, the following can be mentioned:                oxidation by simple exposure to the air;        acid or base or enzymatic hydrolysis during the steps of the preparation of a food, of a supplement, or during the intake thereof (mastication, gastric digestion . . . );        reaction with other components of the diet (chelation and insolubilisation of the metals by the phytic acid contained in the grains and derivatives).        
In turn, the metal chelates are not inert molecules. The metals for example are able to induce oxidations and rancidity, in particular as relates to the double bonds typically present in vegetable oils that are often valuable from a nutritional point of view (such as Ω3 and Ω6, DHA, EPA).
The complexing agents can also have contraindications, due to their chemical characteristics. A typical example is the gastric toxicity of the salicylic acid and salicylates in general due to their interaction with the gastric mucosae.
The object of the present invention is thus to obtain metal complexes capable of overcoming the aforementioned drawbacks.